1. Field of the Invention
The present invention relates to artificial skin and to a method for evaluating UV (ultraviolet ray) screening agents by use of the artificial skin.
2. Related Art
Today, UV screening agents are incorporated into a broad range of skin external compositions, such as cosmetics. Needless to say, when a UV screening agent is incorporated into a skin external composition, the agent must first be tested so as to verify its UV shielding effects.
In such a test, if actual human skin or animal skin is used, results are surely reliable. However, from the viewpoints of safety of the test and prevention of cruelty to animals, tests using living bodies should be avoided if possible.
On the basis of the above standpoint, attempts have been made to test and evaluate UV screening agents by use of artificial skin which mimics the human skin.
For example, in one evaluation method, porous tape (TRANSPORE™ surgical tape, product of 3M Healthcare) is used as a skin substitute membrane (J. Soc. Cosmet. Chem., 40, 127–133, 1989, Diffy & Robson), and in another method, a resin-made skin replica is used as a skin substitute membrane (Int. J. Cos. Sci., 9, 85–98, 1987, Stockdale; Japanese Patent Application Laid-Open (kokai) No. 5-248944). However, the former method, which employs porous tape, is accompanied by the risk that UV screening effects might be overestimated, because the UV screening agent penetrates and is absorbed into the interior of the tape. Meanwhile, in relation to the latter case, silicone resins used as the material for making the resin-made skin replica involve a problem in terms of UV transmission, and urethane resins also used for the same purpose involve a problem in terms of sorption of the UV screening agent.
Accordingly, for evaluating UV screening agents, there is still need for an effective in vitro evaluation method making use of artificial skin having properties as similar as possible to those of real skin, with respect to UV screening agents.